This invention relates to optical connection adapters for use in fiber optical transmission and, more particularly, to an adapter for creating an electrical indication of the condition of the connector.
Optical fiber transmission systems are becoming widely used in the transmission of signals such as data, voice and the like, and in many instances, are replacing traditional electrical systems. Many of the arrangements common to electrical systems, such as coupling, interconnection, splicing, and the like have their counterparts in optical systems but, because of the totally different characteristics of the transmission media, i.e., optical fiber versus metallic wire, connectorization, splicing, and the like involve quit a different apparatus. Where, for example, it is necessary to make a great number of connections in one location, both systems may use what is referred to in the art as patch panels, which provide arrays of connector adapters for interconnection, but the interconnections themselves are generally quite different.
It is common practice in the optical connector art to terminate a length of optical fiber with a connector, an example of which is the SC type connector that is shown and described in U.S. Pat. No. 5,212,752 of Stephenson et al. There are numerous types of such fiber terminating connectors, and, inasmuch as there has been little effort directed to standardization, each type of connector generally requires a different coupling arrangement to permit interconnection of two fibers, for example. The SC and LC connectors are becoming more and more popular, and the remainder of the discussion, in the interest of simplicity, is devoted to such connectors. It is to be understood that the following description of the principles and apparatus of the invention is applicable to other types of connectors as well. As is shown in the Stephenson et al. patent, an SC connector includes a ferrule assembly including a barrel having a collar at one end and an optical fiber terminating ferrule projecting from the barrel. The ferrule assembly is disposed in a plug frame such that an end portion of the ferrule projects from one end of the frame. The plug frame is configured to snap lock into a grip member having a locating key thereon, and the grip is inserted into one side of a slotted coupler adapter, with the locating key inserted into the slot. The grip of a corresponding SC connector is inserted into the other side of the adapter so that the ends of the ferrules abut each other to form a low insertion loss optical interconnection. In the SC connector, the ferrules are spring loaded longitudinally to insure contact between the fiber containing ferrule ends. The entire interconnect operation involves linear motion only and results in a low insertion loss, mechanically stable, protected junction between the two fibers. The expenditure of time in making the interconnection is small and the operator or installer is relieved of having to perform anything other than simple linear motion in plugging the connectors into the coupling adapter.
When large numbers of such interconnections are to be made, it is common practice to use patch panels for holding an array of a large number of coupler adapters. Thus, there can literally be hundreds of such adapters, all in close proximity to each other, mounted in the panel. As long as only a single type of connector, such as the SC connector, is involved, simple adapters may be used for plugging in the connectors from each side of the patch panel. In view of the fact that there are several different types of connectors in widespread use today, it has become common practice to replace the simple adapters with buildout blocks or buildout coupling adapters. In U.S. Pat. No. 5,274,729 of King, et al., there is shown a buildout coupling adapter system in a patch panel that makes possible interconnections among the several different types of connectors in any combination thereof. As can be seen in that patent, a buildout block at one side (or end) thereof is configured the same as a simple coupler adapter having a keyway for receiving, for example, an SC connector. The other end of the buildout block is formed to receive a buildout which may be configured to receive and hold, for example, an SC, an ST, an LC, or an FC connector. Thus, the patch panel may be, on one side thereof, pre-connectorized with optical fibers all of which are terminated by SC connectors, and the other side of the panel is ready to receive pre-connectorized fibers terminated by any one of the numerous connectors. Such an arrangement is more versatile and adaptable than those arrangements which are limited to a single type of pre-connectorized fiber. Such an arrangement also functions well in those installations where one side of the panel is not readily accessible. Thus, the panel can be pre-connectorized before mounting in position on the side which will be relatively inaccessible, after which it can be mounted in place, ready to receive the numerous connections thereto, regardless of connector type.
In any such arrangement there is a potential safety hazard that is often present. Where one or more of the pre-connectorized fibers is carrying optical energy, such energy can be emitted from the end of the fiber connector and pass through the unoccupied buildout block or coupling adapter to the side of the panel where connections are to be made. This optical energy can be harmful for the operator or installer and can be especially harmful to his or her eyes. This hazard is most prevalent when an active connection has to be repaired, cleaned, or otherwise altered by removing an existing connectorized fiber and replacing it with another. In such an instance, it might be difficult or otherwise impractical to shut off the signal transmission in that particular fiber circuit, hence, the installer is forced to deal with a light emitting junction or connection.
This hazard has long been recognized and there are numerous arrangements in the prior art for blocking any light emanating from a fiber connection through an open adapter. In U.S. Pat. No. 5,678,268 of Stephenson, et al., there is shown a pivotable optical shutter arrangement wherein a normally closed pivotable shutter blocks the open exit of an adapter when a connector plug is removed. The shutter advantageously requires only one motion to open it to permit insertion of a plug or connector into the adapter. Such a shutter as shown in the patent is operable by only one hand instead of prior art arrangements which generally require awkward use of two hands by the installer. One of the disadvantages of any shutter arrangement however, is that they are easily xe2x80x9cdefeatablexe2x80x9d in that they can be, during installation of large numbers of connectors and in the interest of expedition, for example, temporarily fixed in the open position, thus contravening their purpose. In addition, the fiber optic transmission art has progressed to the use of higher and higher light energy or power, and has reached a point where shutter arrangements in general have, because of the large light energy, become transparent to much of that energy in the form of infra-red light, which is commonly used. Additionally, when the light intensity is very high, actual damage to the optical connector and the associated fibers can occur.
The present invention is an optical fiber connector adapter assembly wherein the adapter has a sensing mechanism comprising a switching arrangement incorporated therein for signaling associated circuitry to cut off the emission from the light source that supplies the connector plug remaining in the adapter when the first plug is removed. As a consequence, the cessation of light energy emanating from the open receptacle of the adapter assembly is complete, not subject to easy defeat, and eliminates or at least reduces the possibility of damage to the connection, fibers, and users. As will be apparent hereinafter, in some embodiments of the invention, an impending disconnect or connect is signaled, thereby eliminating possible injury to the installer during extraction of the first plug.
In a first illustrative embodiment of the invention, an adapter has first and second leaf springs extending into the plug receiving opening and positional to be pressed into contact with each other when a first plug is inserted into the adapter. The springs are attached to a suitable external circuit, such as a circuit board mounted on or adjacent the adapter, which, upon contact with each other by the leaf springs produces a control signal for turning on the light source, e.g., laser, connected to the second plug already in the adapter. Conversely, when the first plug is removed from the adapter, the circuit is broken and the laser to the second plug is turned off. Thus, the two leaf springs function as a safety switch to prevent light from emanating from an open adapter.
In a second illustrative embodiment of the invention, a light emitting device, such as an LED is mounted in one side wall of the adapter and a light detector in the opposite wall thereof. Thus, light, such as a beam, from the LED directed across the plug receiving portion of the adapter to the detector is detected thereby, in the absence of a first plug, and causes a signal to be directed to a suitable control circuit to prevent the light which normally is directed to a second plug from reaching the adapter generally by extinguishing the laser. When the first plug is inserted into the adapter, it blocks the light path between the LED and detector and the control signal circuit is broken, thereby allowing the laser to the second plug to be turned on.
In still another embodiment of the invention, a Hall effect device, which detects the presence of a magnetic field, is mounted in the adapter on, for example, an end wall thereof or on a circuit board mounted on or in the adapter. In this embodiment, the first plug has a small magnet mounted on the front plug end. When the first plug is inserted into the adapter it is moved forward until it seats therein, at which point the Hall effect device detects the presence of the magnet and produces a signal which, when applied to a control circuit, permits the light (laser) supplying the second plug to be turned on. When the first plug is removed, the magnet is no longer detected and the Hall effect device no longer produces a signal. In the absence of such a signal, the control circuit turns the laser off, or otherwise prevents light from reaching the connector end of the second plug.
In the embodiments of the invention as thus far described the sensing mechanisms produces a signal, either make or break, upon the axial insertion or withdrawal of the first plug. It is often desirable, however, to produce an advance warning of the impending insertion or withdrawal to lessen possible exposure of the operator to light within the adapter while maintaining the simplicity of the foregoing embodiments.
In an embodiment for producing an advance warning, advantage is taken of the LC connector structure which has a cantilevered latching arm thereon for latching the plug to the adapter in the operative position. In order to remove the first plug from the adapter, the latching arm must be depressed to unlatch the plug and enable its removal. In this embodiment of the invention, a Hall effect device is contained in or mounted to the adapter on the outside thereof, and the latching arm has a small magnet affixed thereto near its distal end. The location of the Hall device in the adapter, which is made of a suitable plastic material, is such that it detects the presence of the magnet when the first plug is mounted in its operative position. However, when the latching arm is depressed, the magnet moves away from the Hall device to where the magnetic field thereof is no longer easily detectable and the Hall device signals the control circuit of this condition so that the control circuit shuts off the light supplied to the second plug, even though the first plug has not yet been withdrawn. Thus, the light to the second plug is shut of in anticipation off the removal of the first plug.
In another embodiment for producing an advance warning, a cantilevered leaf spring contact is disposed in the region of the adapter in which the cantilevered latching arm resides when the plug is inserted therein, and a contact pin is affixed within the region adjacent the latching shoulder. When the plug is inserted into the adapter, the latching arm is depressed until the latching lugs or shoulders thereon pair the latching shoulder in the adapter, at which time the arm springs up to engage the latch and the latching lugs and arm force the leaf spring into contact with the contact pin, completing the circuit. When the plug is to be removed, it is necessary that the latching arm first be depressed, breaking the circuit as the latch or latches are disengaged, at which point the latching lugs no longer bear against the leaf spring and it disengages from the contact to break the circuit which the plug is still within the adapter.
In still another embodiment of the invention, use is made of the shutter arrangement of the previously mentioned U.S. Pat. No. 5,678,268. Each sidewall of the pivotable shutter has a depending leg near the distal end of one of which is a light emitting device, e.g. an LED, and the distal end of the other of which is a light detecting device. When the shutter is closed, i.e., there being no first plug in the adapter, the light circuit is completed and the power to the second plug is disabled. However, when the shutter is pivoted upward, the circuit is broken and power to the second plug is resumed. In the ""268 patent, it is shown how pivoting the shutter upward is a function of the plug itself, thus the plug is at least partially inserted before power to the second plug is resumed, thereby protecting the operator. On the other hand, as the first plug is withdrawn, the locations of the LED and detector are such that the power to the second plug is cut off before the first plug is fully withdrawn.
The various principles and features of the present invention are, as will be seen hereinafter, adaptable to numerous other arrangements. While the safety aspects of the present invention are of paramount importance and are treated in detail, the switching capability of the adapter might readily be adapted for other uses that might occur to workers in the art. These principles and features and the advantages thereof will be more readily apparent from the following detailed description, read in conjunction with the accompanying drawings.